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270 Sherman Shortmag (SS)

Idaho Trecker

Well-Known Member
Joined
Apr 19, 2013
Messages
1,465
Location
North Idaho
The first 270 SS is now complete!!! Unfortunately I wont be able to shoot it for a while. I'll try to get some pictures up from my phone shortly. I started this thread to post load data on when I get some going.
 
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I actually have a nightforce and 3 zeiss scopes sitting in the corner... the hold up is time... going to be out of town for work and I don't have my hunting stuff even packed for my elk hunt that opens Saturday. As much as I'd like to get this up and going it's going to be a while. I got the stock opened up to float the barrel tonight but that's it. If for some reason I'm not gone every night this week and my hunting pack loads itself I'll try to get out and post some info.

Work is always in the way of fun unfortunately.

I'm expecting good things from this setup like my 270 Sherman just in a "mountain " Configuration
 
I totally understand. Seems like fall is the best time to get everything done that should have been done in the Spring, especially with regards to work.

Good luck on your elk hunt, which unit are you heading to? I got a 35 tag, worried that there's going to be a lot of competition up there, I haven't hunted it previously.
 
Country... I'm stuck with the general tag since I can't draw a tag to save my life. Just going with the palouse zone. I don't know anything about 35 but good luck.

Got back to town tonight and finished the stock inlet totally, put the 20 moa nightforce bases on along with nightforce rings and 5.5-22x56 and bubble level. Only had time to load one round to get my dies set.

Here's a picture so far
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Don't mind the mess in the background. Only so much room with apartment living.

I haven't had a chance to weigh it in this configuration but will soon. Eventually the nightforce will be swapped out with a zeiss to keep this on the slimmer side.

I still need to clean the barrel, bed the stock, hbn the barrel, and fireform a bunch of brass which I'll use the C.O.W. method. I'm also going to try some 150 grain flat base bonded Matrix in this setup for closer work.

It's coming together and hopefully I'll fill one of my deer tags with it this year.
 
Finally got my dies setup and able to get out to play a little. I have a long throat on this rifle as well which leaves me with a coal of 2.995" at the lands with a 165 grain matrix. I can still run this through the magazine when I decide to finally get a 3" box installed. I fired a few fire forming loads with a very mild charge of rl 26 right at 2600 fps. Thought I might as well have some fun after getting couple through chrono and picked a rock at 845 yards. Dialed up and hit exactly on aim. So far I haven't shot groups of any loads yet.
I ran a short pressure test with rl 33 165 grain matrix and coal of 2.984" today. I ran one shot only of 64.6 65.6 66.5 and 67.6 to see if I could max out pressure... with a couple grains less capacity than the 270 Sherman I was not able to max out with pressure. The highest load was very compressed and the most I could fit. This load had the slightest extractor mark and read 2827 fps. Not to shabby for the 24" barrel and a 165 matrix.
The next purchase will be a quality stock since the factory stock is extremely flimsy.
 
It's actually the other way around... the sherman short (saum parent) has 2 or 4 grains less capacity than the Sherman (270 win parent) my Sherman has a 27" and the SS a 24". The only powder I've shot in both so far is rl 33 and with a compressed load in the ss it only holds 67.6 grains whereas with the long throated Sherman I can pack in 74 grains. It looks like I was able to hit 3156 with the sherman and 2827. It seems like you gain around 50 fps per grain of 33 and the math works out with the charge and barrel length difference so that the 50 fps seems true.
I'll be trying rl 26 next and bet I will max out speed with that faster than any other (I got 3200 fps in Sherman with rl 26).
 
I made it out to run a pressure test with rl 26 and 165 matrix this morning. I maxed out at 3167 fps! Not to shabby for a 24" barrel. That was definitely absolute max just to find it. Probably try some groups around 60 grains. Also going to run some 150 flat base matrix soon and possibly 130 sst for the girlfriend to use if she can step up from my 6mm AI.
 
Havent had much time for shooting lately but made a last minute run to shoot before the major rain and wind hit this morning. I decided to go the other direction on finding loads for this rifle than what I usually do and worked on seating depth first (not powder charge). I loaded 3 each at 3 different seating depths ( .007 off, .060 off and.105 off) with 60 grains of RL 26 Norma brass and Fed 210 GM.
My groups werent spectacular by any means with the weather and my itchy trigger finger todaygun) but I achieved the results I was looking for.

.007 off group at 100 was .890"
.060 off group at 100 was .750"
.105 off group at 100 was 1.050"

I fired all shots over a chrono (just a chrony Nothing fancy) which if i trust the readings also confirmed what my groups told me where I need to be for seating depth. The .060 off load chrono read 2838 2844 2838!!!!

Now if I can get the speed up some and get the groups to shrink I will be in business.

Aslo worth mentioning that since my last outing I put the rifle in a B&C Alaskan stock which I floated the barrel and bedded the recoil lug and tang.

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